Quest: How Secure is Bitcoin?

We have explored how the network hashrate creates a significant barrier for attackers attempting to alter the blockchain.

Now, let's approach the question of Bitcoin's security from a practical perspective:

Many wallets hold large amounts of Bitcoin, and their public addresses are widely known.
Some contain thousands of Bitcoins, yet nobody has ever been able to take the funds.

Example: A Famous Wallet

Visit this well-known wallet:

This wallet is linked to a major fraud involving a company called MtGox in 2011.
It holds approximately 80,000 BTC and has remained untouched since 2011.

 * Despite its contents being worth billions of dollars, nobody has ever succeeded in hacking this wallet.

Imagine a treasure chest with a transparent lid—everyone can see the gold inside, but the chest is protected by an unbreakable combination lock.

Even with billions of dollars in plain sight, no one can crack the lock because the combination is mathematically impossible to guess.

This is the essence of Bitcoin's security:

Even if a public address is known to all, the private key—needed to access the funds—remains secure.
The bounty of 7 billion dollars in this case is an enormous incentive, yet the security of cryptography prevails.

Use Block Chain Explorer to see the Bitcoin address:

1FeexV6bAHb8ybZjqQMjJrcCrHGW9sb6uF

Paste the BTC address above in the search field. (Serach by Address, Txn Hash, Block, Token, Domain Name)
Again, notice that this address is duplicated in the Bitcoin Cash Blockchain.
To complete the task: What is the word hidden by the rectangle in this picture: